As far as I know the IRS or CV rear end did not start in busses until 71. The first three years of Bay window busses had swing axle rear ends just like the splitties. I am pretty positive that
no split window busses ever had CV joints. This is something that could easily vary according to country as well. 67 busses got the 12 volt but it could be ordered as early as 63 as a special
order item. The bolt pattern on the early busses was 5x205.
hope this helps,
Craig
the Gorge VW club
gorgevwclub.com
ps - very much a splitty junkie